Wijeysundera et al1 should be commended for their thought-provoking article suggesting that preoperative medical consultation is associated with worse outcomes. They performed a detailed analysis of administrative data, attempted to minimize bias with appropriate statistical techniques, and found a positive association between preoperative consultation and mortality.
The results, however compelling, are likely a product of confounding by indication, which is a significant problem when using administrative databases. Their propensity score analysis and subgroup analyses served to minimize such bias by equalizing the groups, but statistics alone cannot eliminate it. The proportion of patients with coronary artery disease, diabetes, congestive heart failure, and peripheral vascular disease was equal between the groups because of matching. But what about the severity and number of the underlying comorbidities? The “brittle” diabetic patient is more likely to be referred than the diet-controlled diabetic patient with normoglycemia. The hypertensive patient with a systolic blood pressure of 200 mm Hg is more likely to be referred than the patient with a pressure of 145 mm Hg. Among all of the comorbidities, the sickest and therefore most likely to die are also the most likely to be referred. Propensity matching in an administrative database cannot eliminate this.
Thank you for submitting a comment on this article. It will be reviewed by JAMA Internal Medicine editors. You will be notified when your comment has been published. Comments should not exceed 500 words of text and 10 references.
Do not submit personal medical questions or information that could identify a specific patient, questions about a particular case, or general inquiries to an author. Only content that has not been published, posted, or submitted elsewhere should be submitted. By submitting this Comment, you and any coauthors transfer copyright to the journal if your Comment is posted.
* = Required Field
Disclosure of Any Conflicts of Interest*
Indicate all relevant conflicts of interest of each author below, including all relevant financial interests, activities, and relationships within the past 3 years including, but not limited to, employment, affiliation, grants or funding, consultancies, honoraria or payment, speakers’ bureaus, stock ownership or options, expert testimony, royalties, donation of medical equipment, or patents planned, pending, or issued. If all authors have none, check "No potential conflicts or relevant financial interests" in the box below. Please also indicate any funding received in support of this work. The information will be posted with your response.
Some tools below are only available to our subscribers or users with an online account.
Download citation file:
Web of Science® Times Cited: 7
Customize your page view by dragging & repositioning the boxes below.
More Listings atJAMACareerCenter.com >
Care at the Close of Life: Evidence and Experience
Users' Guides to the Medical Literature
All results at
Enter your username and email address. We'll send you a link to reset your password.
Enter your username and email address. We'll send instructions on how to reset your password to the email address we have on record.
Athens and Shibboleth are access management services that provide single sign-on to protected resources. They replace the multiple user names and passwords necessary to access subscription-based content with a single user name and password that can be entered once per session. It operates independently of a user's location or IP address. If your institution uses Athens or Shibboleth authentication, please contact your site administrator to receive your user name and password.